Metro projects have become an essential infrastructure of modern large metropolitan areas worldwide, as they provide fast, reliable and efficient transportation services, promoting overall mobility, environmental stewardship and economic vitality. In order to assist the decision-making process of pursuing such high cost underground infrastructure, its assessment should not only be based in a purely financial evaluation. On the contrary, the implementation of a comprehensive social cost-benefit analysis incorporating the monetary values of the environmental and social benefits of underground transit systems is an important element to highlight latent qualities. The paper presents an ex-post cost benefit analysis focusing on the last segment of the Athens metro line 3 expansion, from Egaleo to Ag. Marina station. This section has been developed from 2007 and was put in service in 2014. The analysis incorporates actual cost figures from the construction period as well as the operational cost of the segment during the first years of operation. The project is assessed on the grounds of an investment plan using the social NPV and social IRR criteria. The results point out that the project is not feasible if benchmarked against purely financial criteria. Nevertheless, the introduction of the monetary values attained by the social and environmental benefits that the project brings, renders the whole development desirable and beneficial from a cost-benefit analysis standpoint.

地铁项目已成为全球现代大都市地区的重要基础设施，因为它们提供快速、可靠和高效的交通服务，促进整体流动性、环境管理和经济活力。为了协助追求如此​​高成本的地下基础设施的决策过程，其评估不应仅基于纯粹的财务评估。相反，实施综合社会成本效益分析，结合地下交通系统的环境和社会效益的货币价值，是突出潜在品质的重要因素。本文介绍了一项事后成本效益分析，重点关注雅典地铁 3 号线扩建的最后一段，从 Egaleo 到 Ag。滨海站。该部分从 2007 年开始开发，并于 2014 年投入使用。分析结合了建设期的实际成本数据以及该部分在运营头几年的运营成本。该项目根据使用社会 NPV 和社会 IRR 标准的投资计划进行评估。结果表明，如果以纯粹的财务标准为基准，该项目是不可行的。尽管如此，从成本效益分析的角度来看，引入项目带来的社会和环境效益所获得的货币价值，使整个开发项目变得可取和有益。该分析结合了建设期的实际成本数据以及该部门在运营头几年的运营成本。该项目根据使用社会 NPV 和社会 IRR 标准的投资计划进行评估。结果表明，如果以纯粹的财务标准为基准，该项目是不可行的。尽管如此，从成本效益分析的角度来看，引入项目带来的社会和环境效益所获得的货币价值，使整个开发项目变得可取和有益。该分析结合了建设期的实际成本数据以及该部门在运营头几年的运营成本。该项目根据使用社会 NPV 和社会 IRR 标准的投资计划进行评估。结果表明，如果以纯粹的财务标准为基准，该项目是不可行的。尽管如此，从成本效益分析的角度来看，引入项目带来的社会和环境效益所获得的货币价值，使整个开发项目变得可取和有益。